The present invention pertains to a system utilizing recirculating porous foam rubber balls as a tube cleaning media and, more particularly, to an apparatus for collecting and removing balls from the system and for adding new balls to the system.
It is well known in the art to provide the condenser in a heat exchanger with a large number of parallel tubes through which cooling water is directed. The condenser tubes are supplied with cooling water by a pump-operated recirculating system, typically receiving water from a cooling tower, circulating it through the heat exchanger condenser and returning it to the cooling tower.
Various methods are utilized for periodically cleaning the condenser tubes to remove deposits which accumulate therein. Typically, the condenser tubes may be about 1" in diameter and, in one known method, resilient foam rubber balls having a diameter slightly larger than the tubes are circulated therethrough with the cooling water. The balls are compressed slightly as they enter the tubes and are forced through the tubes by water pressure carrying accumulated deposits with them. The balls are injected into the cooling water flow from a parallel branch upstream from the condenser and are removed from the stream after they exit the condenser and diverted from the main cooling water flow back into the parallel branch for recirculation or collection. To separate the balls from the return flow to the cooling tower, a ball strainer comprising a large screen is disposed in the return flow piping system where the balls are screened from the flow and diverted into the collection/recirculation branch.
Balls which are diverted from the main cooling water stream by the ball strainer and shunted into the parallel recirculation branch are delivered to a ball collector apparatus which, in typical prior art systems, may be operated to allow the balls to flow directly therethrough for recirculation, to collect and hold the balls while allowing only the water to continue through the collector, or to discharge the balls from the system. The porous foam rubber balls used in these systems may have diameters in the range typically less than 1 1/2" (just slightly larger than the condenser tubes through which they are forced to pass). Abrasive wear on the balls eventually reduces their diameter and requires them to be replaced. Thus, a ball collector apparatus also typically provides a means for adding new balls to the system to replace those discharged after collection.
One common prior art ball collector apparatus includes a collector housing having a removable perforated basket inside. The water flow in the recirculation branch from the ball strainer, including the saturated balls, is passed into the perforated basket which has a bottom door that is left open to allow the balls to recirculate through the heat exchanger and which is closed when it is desired to collect the balls. Once the balls are collected, flow through the collector housing is terminated and the basket is lifted out of the housing. This prior art apparatus requires complex mechanisms for opening and closing the door in the lower portion of the basket and still permitting removal of the basket from the collector housing. In a prior art variation of the foregoing apparatus, the collecting basket does not have to be lifted from the housing to remove the balls, but rather direct axis to the basket through the housing side wall is provided which, when open, allows the balls to tumble by gravity out of the basket and housing. However, this apparatus still requires a basket opening mechanism for recirculating flow, and an additional mechanism to operate the side discharge door.
U.S. Pat. No. 4,620,589 discloses an apparatus for diverting the cleaning balls from the main cooling water flow and an apparatus for collecting the balls and removing them from the parallel recirculation branch. The collecting and removing device operates in essentially the same manner as the removable basket previously described, except that the entire portion of the collector housing including the basket form a separable lock which can be isolated and completely removed from the system, the worn balls are removed from the lock and the lock is refilled with new balls and reinserted in the system.
It is necessary or highly desirable to somehow de-aerate new dry balls which are added to a ball cleaning system. Although the balls are porous and absorbent, they are not easily saturated by the cooling water without initial de-aeration, e.g. by squeezing or the like.
U.S. Pat. No. 4,314,604 describes an apparatus for sizing balls which have been removed from a system to take out of service those which are undersized and to return for readdition to the system those which are still large enough. The system also includes an apparatus for de-aerating balls returned to or initially put into service by squeezing them between a pair of counter rotating rolls immersed in water. It is also known to de-aerate dry balls outside of a ball collector by evacuating a container of water with dry balls floating thereon. However, the saturated balls must then be transferred into the system via the ball collector housing or at some other convenient point.
It is apparent, therefore, that prior art systems and apparatus for cleaning ball collection, removal and addition are mechanically complex and cumbersome to operate. It is well known that the complexity of these devices also substantially shortens their operating life, leading to costly and time consuming repair and replacement. The addition of new cleaning balls to a system by various means external to the ball collecting and discharge apparatus also leaves much to be desired.